Deterministic radiation damage has a threshold dose value below which the effect does not occur. If the threshold dose is exceeded, the severity of the effect increases with increasing dose. Examples for deterministic effects are skin erythema and epilation.

Of a random nature. Radiation effects are referred to as "stochastic" when the probability of a damage resulting from radiation increases with increments of dose, whereas the severity of damage is not affected by the dose. Cancer and leukaemia are examples for stochastic damage.

Radiation doses exceeding a threshold of about 500 millisieverts (mSv) can cause tissue reactions in the human body, also called deterministic effects. They are the result of a massive cell killing and the subsequent loss of function of the affected organs or tissues. Particularly

the skin,

the hair, and

the gastrointestinal epithelium

are affected. Above the dose-threshold, the severity of the injury increases with dose and the damage appears earlier after higher doses.

Acute radiation injuries

Acute radiation injuries are counted among deterministic radiation effects or tissue reactions. They occur shortly (within days and weeks) after high radiation exposures, for example after a nuclear accident. Acute radiation effects comprise among others:

Late deterministic effects

Usually, deterministic effects are acute effects. Still, there are some late deterministic effects like pulmonary fibrosis (increase in fibrous connective tissue leading to loss of pulmonary function). It appears 6 to 24 months after exposure.